1. Field of the Invention
The present invention relates to an optical communication network, and more particularly, to an improved alarm suppressing method for an optical transmission apparatus which is capable of promptly retrieving problems in an optical communication network.
2. Description of the Background Art
In general, a communication network is formed of a plurality of different elements manufactured from different makers. The communication elements generate alarm when there occurs a fault in its own or internal connections. Since the network elements don""t recognize topology of communication network, a single fault in the communication network may seriously influence on the operation of other different elements and as a result there may occur a plurality of secondary alarms from the elements. Here, the former alarm is referred to as a root alarm and the latter as a propagation alarm.
Presently, a communication network management is manually controlled by humans. An operator in a central control chamber is directed to analyze kinds of alarms, generated locations, kinds of discharged alarms and locations, etc., on the ground of alarms displayed on a console and users"" dissatisfaction. An appropriate solution has been taken according to the analyses. Therefore, if there occurs an error in a single optical line with regard to an optical communication device, it inevitably leads to a communication malfunctioning to a plurality of subscribers. Accordingly, it has been understood significant to analyze the root and propagation alarms with regard to maintenance and management of optical communication devices.
FIG. 1 is a block diagram illustrating an entire network interfacing of a synchronous optical transmission devices, wherein a first linear network 100, a second linear network 110 and a ring mode network 120 are interfaced to an EMS(element management system) 38 through a LAN (local area network) 36.
At this time, respective network elements NE in the first and second linear networks 100, 110 and in the ring mode network 120 have different names depending upon their locations. That is, the network elements 10, 12, 14,22 in the first and second linear networks 100, 110 are respectively referred to as a TM (terminal multiplexer) since they form terminal elements. The network elements 16, 18, 20 disposed in the middle of the second linear network 110 are respectively called as an ADM (add drop multiplexer). Also, the network elements 24, 26, 28, 30,32,34 in the ring mode network 120 are respectively referred to as an RM (ring multiplexer).
The EMS 38 serves to monitor the root alarm and propagation alarms generated from the respective network elements NE and the operator employs a computer to implement maintenance and management of optical communication lines.
The optical communication device SDH155 (synchronous digital hierarchy 155) employed in the present invention enables communication through 155 Mbps high speed transmission. Here, one optical line represents 1900 lines of telephone circuit. Typically, an optical communication device is required to include two optical lines: one for reception, the other for transmission. Here, a preliminary line may be reserved when necessary.
Specifically, one optical line may be used as 3 lines of 36 Mbps VC3 (virtual container 3) class and 63 lines of 2.048 Mbps VC12 class, one line of VC3 class and 42 lines of VC12 class, or 2 lines of VC3 class and 21 lines of VC12 class.
FIGS. 2 and 3 show circuit connections at a linear mode and a ring mode, respectively, according to the conventional art. With reference to the drawings, the alarm suppressing method for an optical transmission apparatus will now be explained. For convenience""s sake, it is assumed that one line of VC 3 class and 42 lines of VC 12 class are employed as an optical line and an example will be taken in a state in which the optical line 42 of the element 34 in the ring mode network 110 is shorted and causes an obstacle.
As shown in FIGS. 3 and 4, when the optical line 42 is broken, the element 34 generates a root alarm STM1LOS (LOS denotes loss of signal) of its own through the optical line 42, and the element 34 transmits to the element 32 a propagation alarm with the information that the element 34 has generated the root alarm STM1LOS toward west direction W. As a result, the propagation alarm MSRDI (RDI denotes remote defect indication) is detected from east direction E of the element 32.
Also, the element 34 generates one propagation alarm TU3AIS (AIS denotes alarm indication signal) and generates 42 propagation alarms TU12AIS through the VC12 class circuit. Accordingly, the propagation alarm TU3AIS is transmitted to the element 28 at a terminal point of the VC3 class circuit through the optical lines 44, 45, 46. The propagation alarm TU12AIS is transmitted to the element 26 at a terminal point of the VC12 class through the optical line 45. As a result, the propagation alarm TU3AIS of VC3 class circuit is detected at west direction W of each of the elements 24, 26, 28, and the propagation alarm TU12AIS of VC12 class circuit is detected at west direction W of the element 26. At this time, the propagation alarm TU3AIS is detected from each of the elements 24, 26, 28 with regard to VC3 class line, and the propagation alarm TU12AIS is detected from the element 26 serving as an end terminal, with regard to VC3 class lines.
Therefore, the element 28 serving as an end terminal of the VC3 class line transmits the other propagation alarms VC3RDI toward both directions thereof through the optical line 46xe2x80x2, 47, and the element 26 serving as an end terminal transmits 42 lines of the other propagation alarm VC12RDI toward both directions thereof through the optical line 45xe2x80x2, 46. As a result, the propagation alarm VC3RDI is detected at the element 32 serving as the end terminal of the VC3 class, and the 42 lines of the propagation alarm VC12RDI is detected at the element 30 serving as the end terminal.
Consequently, through the LAN 36 the EMS 38 detects one root alarm LOS, one propagation alarm MSRDI, three propagation alarms TU3AIS, 42 propagation alarms TU12AIS, one VC3 class propagation alarm VC3RDI, 42 VC12 class propagation alarms VC12RDI. Therefore, the system operator analyzes 90 alarms in total which are displayed on the EMS 38 and understands the connection of the propagation alarms generated from the root alarm LOS and the alarm using the locations and the connection state of the respective elements. Also, in the linear mode network 100, the same steps as above are taken to understand the optical line which has generated the root alarms.
However, the conventional alarm suppressing method of an optical transmission apparatus requires an operation of ability to recognize mutual connection of the alarms by analyzing a plurality of alarms detected. Further, the conventional alarm suppressing method of the conventional optical transmission apparatus may delay solution of breakdown and incur a time loss, thereby deteriorating system reliability.
The present invention is directed to overcoming disadvantages of the conventional alarm suppressing method for an optical transmission apparatus.
Therefore, it is an object of the present invention to provide an alarm suppressing method for an optical transmission method capable of automatically analyzing a mutual relation between root alarm and propagation alarm.
It is another object of the present invention to provide an alarm suppressing method for an optical transmission method enabling a prompt implementation of maintenance and management of optical lines by recognizing the optical lines of root alarm generation and analyzing the mutual relation between root alarm and propagation alarm within a short time period.
To achieve the above-described objects, there is provided an alarm suppressing method for an optical transmission apparatus according to the present invention which includes the steps of checking whether a detected alarm is a root alarm, suppressing a first propagation alarm generated by the root alarm when the detected alarm is a root alarm, determining the types of network elements, suppressing a second propagation alarm generated by the root alarm in accordance with the determined types of the network elements, and suppressing a third propagation alarm generated in accordance with the second propagation alarm.
Further, to achieve the above-described objects, there is provided an alarm suppressing method for an optical transmission apparatus according to the present invention which includes the steps of recognizing the direction of a detected propagation alarm, retrieving an element next to the recognized direction, checking the kind of the generated propagation alarm, and suppressing a corresponding propagation alarm when a data base includes a root alarm by retrieving from the data base the information relevant to the root alarm in accordance with the kinds of the checked alarms.
The features and advantages of the present invention will become more readily apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific example, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.